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setmode.c revision 1.8 
      1 /*
      2  * Copyright (c) 1989 The Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 /*static char *sccsid = "from: @(#)setmode.c	5.6 (Berkeley) 5/27/91";*/
     36 static char *rcsid = "$Id: setmode.c,v 1.8 1994/02/11 05:55:45 cgd Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/types.h>
     40 #include <sys/stat.h>
     41 #include <signal.h>
     42 #include <errno.h>
     43 #include <stddef.h>
     44 #ifdef SETMODE_DEBUG
     45 #include <stdio.h>
     46 #endif
     47 #include <stdlib.h>
     48 #include <ctype.h>
     49 
     50 #define	SET_LEN	6		/* initial # of bitcmd struct to malloc */
     51 #define	SET_LEN_INCR 4		/* # of bitcmd structs to add as needed */
     52 
     53 typedef struct bitcmd {
     54 	char	cmd;
     55 	char	cmd2;
     56 	mode_t	bits;
     57 } BITCMD;
     58 
     59 #define	CMD2_CLR	0x01
     60 #define	CMD2_SET	0x02
     61 #define	CMD2_GBITS	0x04
     62 #define	CMD2_OBITS	0x08
     63 #define	CMD2_UBITS	0x10
     64 
     65 static BITCMD	*addcmd __P((BITCMD *, int, int, int, u_int));
     66 static int	 compress_mode __P((BITCMD *));
     67 #ifdef SETMODE_DEBUG
     68 static void	 dumpmode __P((BITCMD *));
     69 #endif
     70 
     71 /*
     72  * Given the old mode and an array of bitcmd structures, apply the operations
     73  * described in the bitcmd structures to the old mode, and return the new mode.
     74  * Note that there is no '=' command; a strict assignment is just a '-' (clear
     75  * bits) followed by a '+' (set bits).
     76  */
     77 mode_t
     78 getmode(bbox, omode)
     79 	void *bbox;
     80 	mode_t omode;
     81 {
     82 	register BITCMD *set;
     83 	register mode_t newmode, value;
     84 
     85 	set = (BITCMD *)bbox;
     86 	newmode = omode;
     87 	for (value = 0;; set++)
     88 		switch(set->cmd) {
     89 		/*
     90 		 * When copying the user, group or other bits around, we "know"
     91 		 * where the bits are in the mode so that we can do shifts to
     92 		 * copy them around.  If we don't use shifts, it gets real
     93 		 * grundgy with lots of single bit checks and bit sets.
     94 		 */
     95 		case 'u':
     96 			value = (newmode & S_IRWXU) >> 6;
     97 			goto common;
     98 
     99 		case 'g':
    100 			value = (newmode & S_IRWXG) >> 3;
    101 			goto common;
    102 
    103 		case 'o':
    104 			value = newmode & S_IRWXO;
    105 common:			if (set->cmd2 & CMD2_CLR) {
    106 				mode_t clrval;
    107 
    108 				clrval =
    109 				    (set->cmd2 & CMD2_SET) ?  S_IRWXO : value;
    110 
    111 				if (set->cmd2 & CMD2_UBITS)
    112 					newmode &= ~((clrval<<6) & set->bits);
    113 				if (set->cmd2 & CMD2_GBITS)
    114 					newmode &= ~((clrval<<3) & set->bits);
    115 				if (set->cmd2 & CMD2_OBITS)
    116 					newmode &= ~(clrval & set->bits);
    117 			}
    118 			if (set->cmd2 & CMD2_SET) {
    119 				if (set->cmd2 & CMD2_UBITS)
    120 					newmode |= (value<<6) & set->bits;
    121 				if (set->cmd2 & CMD2_GBITS)
    122 					newmode |= (value<<3) & set->bits;
    123 				if (set->cmd2 & CMD2_OBITS)
    124 					newmode |= value & set->bits;
    125 			}
    126 			break;
    127 
    128 		case '+':
    129 			newmode |= set->bits;
    130 			break;
    131 
    132 		case '-':
    133 			newmode &= ~set->bits;
    134 			break;
    135 
    136 		case 'X':
    137 			if (omode & (S_IFDIR|S_IXUSR|S_IXGRP|S_IXOTH))
    138 				newmode |= set->bits;
    139 			break;
    140 
    141 		case '\0':
    142 		default:
    143 #ifdef SETMODE_DEBUG
    144 			(void)printf("getmode:%04o -> %04o\n", omode, newmode);
    145 #endif
    146 			return (newmode);
    147 		}
    148 }
    149 
    150 #define	ADDCMD(a, b, c, d) \
    151 	if (set >= endset) { \
    152 		register BITCMD *newset; \
    153 		setlen += SET_LEN_INCR; \
    154 		newset = realloc(saveset, sizeof(BITCMD) * setlen); \
    155 		if (!saveset) \
    156 			return (NULL); \
    157 		set = newset + (set - saveset); \
    158 		saveset = newset; \
    159 		endset = newset + (setlen - 2); \
    160 	} \
    161 	set = addcmd(set, (a), (b), (c), (d))
    162 
    163 #define	STANDARD_BITS	(S_ISUID|S_ISGID|S_IRWXU|S_IRWXG|S_IRWXO)
    164 
    165 void *
    166 setmode(p)
    167 	register char *p;
    168 {
    169 	register int perm, who;
    170 	register char op;
    171 	BITCMD *set, *saveset, *endset;
    172 	sigset_t sigset, sigoset;
    173 	mode_t mask;
    174 	int equalopdone, permXbits, setlen;
    175 
    176 	if (!*p)
    177 		return (NULL);
    178 
    179 	/*
    180 	 * Get a copy of the mask for the permissions that are mask relative.
    181 	 * Flip the bits, we want what's not set.  Since it's possible that
    182 	 * the caller is opening files inside a signal handler, protect them
    183 	 * as best we can.
    184 	 */
    185 	sigfillset(&sigset);
    186         (void)sigprocmask(SIG_BLOCK, &sigset, &sigoset);
    187 	(void)umask(mask = umask(0));
    188 	mask = ~mask;
    189         (void)sigprocmask(SIG_SETMASK, &sigoset, NULL);
    190 
    191 	setlen = SET_LEN + 2;
    192 
    193 	if ((set = malloc((u_int)(sizeof(BITCMD) * setlen))) == NULL)
    194 		return (NULL);
    195 	saveset = set;
    196 	endset = set + (setlen - 2);
    197 
    198 	/*
    199 	 * If an absolute number, get it and return; disallow non-octal digits
    200 	 * or illegal bits.
    201 	 */
    202 	if (isdigit(*p)) {
    203 		perm = (mode_t)strtol(p, (char **)0, 8);
    204 		if (perm & ~(STANDARD_BITS|S_ISTXT)) {
    205 			free(saveset);
    206 			return (NULL);
    207 		}
    208 		while (*++p)
    209 			if (*p < '0' || *p > '7') {
    210 				free(saveset);
    211 				return (NULL);
    212 			}
    213 		ADDCMD('=', (STANDARD_BITS|S_ISTXT), perm, mask);
    214 		return (saveset);
    215 	}
    216 
    217 	/*
    218 	 * Build list of structures to set/clear/copy bits as described by
    219 	 * each clause of the symbolic mode.
    220 	 */
    221 	for (;;) {
    222 		/* First, find out which bits might be modified. */
    223 		for (who = 0;; ++p) {
    224 			switch (*p) {
    225 			case 'a':
    226 				who |= STANDARD_BITS;
    227 				break;
    228 			case 'u':
    229 				who |= S_ISUID|S_IRWXU;
    230 				break;
    231 			case 'g':
    232 				who |= S_ISGID|S_IRWXG;
    233 				break;
    234 			case 'o':
    235 				who |= S_IRWXO;
    236 				break;
    237 			default:
    238 				goto getop;
    239 			}
    240 		}
    241 
    242 getop:		if ((op = *p++) != '+' && op != '-' && op != '=') {
    243 			free(saveset);
    244 			return (NULL);
    245 		}
    246 		if (op == '=')
    247 			equalopdone = 0;
    248 
    249 		who &= ~S_ISTXT;
    250 		for (perm = 0, permXbits = 0;; ++p) {
    251 			switch (*p) {
    252 			case 'r':
    253 				perm |= S_IRUSR|S_IRGRP|S_IROTH;
    254 				break;
    255 			case 's':
    256 				/* If only "other" bits ignore set-id. */
    257 				if (who & ~S_IRWXO)
    258 					perm |= S_ISUID|S_ISGID;
    259 				break;
    260 			case 't':
    261 				/* If only "other" bits ignore sticky. */
    262 				if (who & ~S_IRWXO) {
    263 					who |= S_ISTXT;
    264 					perm |= S_ISTXT;
    265 				}
    266 				break;
    267 			case 'w':
    268 				perm |= S_IWUSR|S_IWGRP|S_IWOTH;
    269 				break;
    270 			case 'X':
    271 				permXbits = S_IXUSR|S_IXGRP|S_IXOTH;
    272 				break;
    273 			case 'x':
    274 				perm |= S_IXUSR|S_IXGRP|S_IXOTH;
    275 				break;
    276 			case 'u':
    277 			case 'g':
    278 			case 'o':
    279 				/*
    280 				 * When ever we hit 'u', 'g', or 'o', we have
    281 				 * to flush out any partial mode that we have,
    282 				 * and then do the copying of the mode bits.
    283 				 */
    284 				if (perm) {
    285 					ADDCMD(op, who, perm, mask);
    286 					perm = 0;
    287 				}
    288 				if (op == '=')
    289 					equalopdone = 1;
    290 				if (op == '+' && permXbits) {
    291 					ADDCMD('X', who, permXbits, mask);
    292 					permXbits = 0;
    293 				}
    294 				ADDCMD(*p, who, op, mask);
    295 				break;
    296 
    297 			default:
    298 				/*
    299 				 * Add any permissions that we haven't already
    300 				 * done.
    301 				 */
    302 				if (perm || (op == '=' && !equalopdone)) {
    303 					if (op == '=')
    304 						equalopdone = 1;
    305 					ADDCMD(op, who, perm, mask);
    306 					perm = 0;
    307 				}
    308 				if (permXbits) {
    309 					ADDCMD('X', who, permXbits, mask);
    310 					permXbits = 0;
    311 				}
    312 				goto apply;
    313 			}
    314 		}
    315 
    316 apply:		if (!*p)
    317 			break;
    318 		if (*p != ',')
    319 			goto getop;
    320 		++p;
    321 	}
    322 	set->cmd = 0;
    323 #ifdef SETMODE_DEBUG
    324 	(void)printf("Before compress_mode()\n");
    325 	dumpmode(saveset);
    326 #endif
    327 	compress_mode(saveset);
    328 #ifdef SETMODE_DEBUG
    329 	(void)printf("After compress_mode()\n");
    330 	dumpmode(saveset);
    331 #endif
    332 	return (saveset);
    333 }
    334 
    335 static BITCMD *
    336 addcmd(set, op, who, oparg, mask)
    337 	BITCMD *set;
    338 	register int oparg, who;
    339 	register int op;
    340 	u_int mask;
    341 {
    342 	switch (op) {
    343 	case '+':
    344 	case 'X':
    345 		set->cmd = op;
    346 		set->bits = (who ? who : mask) & oparg;
    347 		break;
    348 
    349 	case '-':
    350 		set->cmd = '-';
    351 		set->bits = (who ? who : (S_IRWXU|S_IRWXG|S_IRWXO)) & oparg;
    352 		break;
    353 
    354 	case '=':
    355 		set->cmd = '-';
    356 		if (!who) {
    357 			set->bits = STANDARD_BITS;
    358 			who = mask;
    359 		} else
    360 			set->bits = who;
    361 		set++;
    362 
    363 		set->cmd = '+';
    364 		set->bits = who & oparg;
    365 		break;
    366 	case 'u':
    367 	case 'g':
    368 	case 'o':
    369 		set->cmd = op;
    370 		if (who) {
    371 			set->cmd2 = ((who & S_IRUSR) ? CMD2_UBITS : 0) |
    372 				    ((who & S_IRGRP) ? CMD2_GBITS : 0) |
    373 				    ((who & S_IROTH) ? CMD2_OBITS : 0);
    374 			set->bits = ~0;
    375 		} else {
    376 			set->cmd2 = CMD2_UBITS | CMD2_GBITS | CMD2_OBITS;
    377 			if (oparg == '-')
    378 				set->bits = (S_IRWXU|S_IRWXG|S_IRWXO);
    379 			else
    380 				set->bits = mask;
    381 		}
    382 
    383 		if (oparg == '+')
    384 			set->cmd2 |= CMD2_SET;
    385 		else if (oparg == '-')
    386 			set->cmd2 |= CMD2_CLR;
    387 		else if (oparg == '=')
    388 			set->cmd2 |= CMD2_SET|CMD2_CLR;
    389 		break;
    390 	}
    391 	return (set + 1);
    392 }
    393 
    394 #ifdef SETMODE_DEBUG
    395 static void
    396 dumpmode(set)
    397 	register BITCMD *set;
    398 {
    399 	for (; set->cmd; ++set)
    400 		(void)printf("cmd: '%c' bits %04o%s%s%s%s%s%s\n",
    401 		    set->cmd, set->bits, set->cmd2 ? " cmd2:" : "",
    402 		    set->cmd2 & CMD2_CLR ? " CLR" : "",
    403 		    set->cmd2 & CMD2_SET ? " SET" : "",
    404 		    set->cmd2 & CMD2_UBITS ? " UBITS" : "",
    405 		    set->cmd2 & CMD2_GBITS ? " GBITS" : "",
    406 		    set->cmd2 & CMD2_OBITS ? " OBITS" : "");
    407 }
    408 #endif
    409 
    410 /*
    411  * Given an array of bitcmd structures, compress by compacting consecutive
    412  * '+', '-' and 'X' commands into at most 3 commands, one of each.  The 'u',
    413  * 'g' and 'o' commands continue to be separate.  They could probably be
    414  * compacted, but it's not worth the effort.
    415  */
    416 static int
    417 compress_mode(set)
    418 	register BITCMD *set;
    419 {
    420 	register BITCMD *nset;
    421 	register int setbits, clrbits, Xbits, op;
    422 
    423 	for (nset = set;;) {
    424 		/* Copy over any 'u', 'g' and 'o' commands. */
    425 		while ((op = nset->cmd) != '+' && op != '-' && op != 'X') {
    426 			*set++ = *nset++;
    427 			if (!op)
    428 				return;
    429 		}
    430 
    431 		for (setbits = clrbits = Xbits = 0;; nset++) {
    432 			if ((op = nset->cmd) == '-') {
    433 				clrbits |= nset->bits;
    434 				setbits &= ~nset->bits;
    435 				Xbits &= ~nset->bits;
    436 			} else if (op == '+') {
    437 				setbits |= nset->bits;
    438 				clrbits &= ~nset->bits;
    439 				Xbits &= ~nset->bits;
    440 			} else if (op == 'X')
    441 				Xbits |= nset->bits & ~setbits;
    442 			else
    443 				break;
    444 		}
    445 		if (clrbits) {
    446 			set->cmd = '-';
    447 			set->cmd2 = 0;
    448 			set->bits = clrbits;
    449 			set++;
    450 		}
    451 		if (setbits) {
    452 			set->cmd = '+';
    453 			set->cmd2 = 0;
    454 			set->bits = setbits;
    455 			set++;
    456 		}
    457 		if (Xbits) {
    458 			set->cmd = 'X';
    459 			set->cmd2 = 0;
    460 			set->bits = Xbits;
    461 			set++;
    462 		}
    463 	}
    464 }
    465